I just noticed a few days ago that the stickers I give to other sims are not sticking. This happens to SOME sims not all the sims I try to give stickers.
What happens is that I have to attempt twice to give a sticker to a sim. The first attempt usually isn't completed so I have to tap the sim again to give the sticker.
I'll post if it happens again.
I noticed a variation of this happening at a party I attended yesterday, I thought it might've been related to the update. I gave out some stickers, then when I went to stick another sim it would show 5 cool stickers even though I had given out 2, etc. I could tap on the Sims i had stickered and half of the ones I had stickered still had the option since they hadn't stuck. It seemed like the second time I tried they did stick though, not quite what you mentioned re: them never sticking.
I'm on version 13 of TSM and was playing with stable WiFi connection.
I noticed that it is most likely a connection issue.
I used to have to give the same sim stickers 2x for it to stick.
But then the solution that work for me was:
Give the sticker and not click away from the sim I was giving immediately, because clicking away immediately probably made it not sync completely.
Or give them and then wait, sometimes after a few sec up to 1 minute and they get it. No need to give them a 2nd time if it looks like they didn't get the 1st.
It still happens, but very rare (at least for me) and it can be a problem if they are many people at your party and your not sure who you've already given stickers and you end up giving them 2x. In such a case, you just have to remember who you've already given.